AGCI research programme: Climate Science and Ecohydrology

AGCI postdoc: Marjan van de Weg

Improving a next generation DGVM by implementing dynamic plant traits

This post-doc project utilizes different types of datasets (plant traits and eddy flux data) for approaching ecosystem functioning, especially the biological controls on carbon (C) and H2O fluxes, in a novel way. On a leaf level, plant traits (such as foliar nitrogen (N), leaf mass per area) are known to determine biochemical capacity for C uptake and transpiration. But on larger scales, vegetation is currently represented mostly by so called plant functional types (PFTs). The variance of the plant traits within these PFTs is as large as between them, however, which shows that PFTs do not necessary represent patterns of plant traits as found worldwide. Therefore, we want to find a more informed way of to analyze ecosystem C and H2O fluxes at global scale. To do so, we use species plant traits, from the established plant trait database TRY (www.TRY-db.org) as well as traits measured in situ, rather than PFTs to represent vegetation. As for the global C and H2O fluxes, we use with FLUXNET data to derive ecosystem functional properties (such as the gross productivity at a given radiation level, or the temperature sensitivity of ecosystem respiration).

Short CV

Marjan’s research so far has focused on the controls of different processes that underpin the global C cycle (i.e. photosynthesis and respiration). Her first introduction in eco-physiological work was as a MSc student in the Systems Ecology group at the VU University Amsterdam, for which she measured ecosystem respiration in a long-term warming experiment in Abisko, Sweden. Since then, she carried out research in a variety of other ecosystems, ranging from tropical cloud forests to agricultural wetlands and the North Slope of Alaska.

Her PhD research focused on how leaf traits, together with environmental parameters, control the CO2 uptake of a tropical montane cloud forest. This included fieldwork in the Peruvian Andes, as well as the use of the ecosystem parameters derived from that fieldwork in a soil-plant-atmosphere model (the SPA model from Mat Williams) for scaling stand level carbon uptake.

Her post-doc at the Marine Biological Laboratory consisted of projects investigating the effects of environmental change (e.g. increased nutrient availability, species shifts, increased fire) on the C and N cycle in the Alaskan tundra. This included working in the Arctic LTER (Long Term Ecological Research) sites at the Toolik Lake field station in Alaska, as well as work at a large tundra fire scar from 2007 on the North Slope.